Eppler made his professional debut with the Jamestown Jammers,[4] pitching in 14 games, posting a 2.49 ERA. He played 2015 with the Bradenton Marauders and Altoona Curve, going 6–2 with a 3.14 ERA in 15 games. After the season he played in the Arizona Fall League. He spent 2016 with Altoona, pitching to a 9–1 record and 3.99 ERA in a career high 162.1 innings pitched. He spent 2017 with the Indianapolis Indians,[5] posting an 8–9 record with a 4.89 ERA.[6] Eppler returned to the Indians in 2018, going 13–6 with a 3.59 ERA in 28 games (25 starts).[7]
Orix Buffaloes
On January 15, 2019, the Orix Buffaloes purchased Eppler's contract from the Pirates.[8] In 24 games for Orix, he recorded a 4–4 record and 4.02 ERA with 25 strikeouts across 31+1⁄3 innings pitched. On December 2, Eppler became a free agent.[9]
Washington Nationals
On January 9, 2020, Eppler signed a minor league deal with the Washington Nationals. Eppler did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[10] In 2021, Eppler appeared in 19 games for the Triple-A Rochester Red Wings, posting a 7.75 ERA with 48 strikeouts. On August 24, 2021, Eppler was released by the Nationals.
Kiwoom Heroes
On December 17, 2021, Eppler signed a one-year, $400,000 deal with the Kiwoom Heroes of the KBO League.[11] He became a free agent after the 2022 season.
Fubon Guardians
On January 5, 2023, Eppler signed with the Fubon Guardians of the Chinese Professional Baseball League.[12] Eppler made 9 starts for Fubon, posting a 3–1 record and 2.89 ERA with 30 strikeouts in 56.0 innings pitched. On June 21, he was released by the Guardians. The release was made after Eppler decided to terminate the contract early for personal reasons.[13]
Sultanes de Monterrey
On June 30, 2023, Eppler signed with the Sultanes de Monterrey of the Mexican League.[14] In 7 starts for Monterrey, Eppler registered a 4–1 record and 4.23 ERA with 27 strikeouts across 38+1⁄3 innings pitched.